To determine whether this difference arose from a shift within CSF CD4+ T cell subsets or from additional invading CD4+ T cells, we calculated absolute counts of each T cell subpopulation and normalized these to CD14+ monocyte counts (Supplementary Fig. S3B) according to our previous work.6 We then analysed ratios of CD4+ T cell subsets to CD14+ counts in controls versus MS and MS1 versus MS2 patients, confirming the subset distribution observed with our algorithm (Fig. 4C). Here, CD14 is linked to myeloid sarcoma.